用于海水淡化的MFI型分子筛膜制备及其反渗透脱盐传递机理研究

Seawater desalination is a prospective approach to address the global water shortage.The water productivity and energy cost of Reverse Osmosis(RO) technology, one of major seawater desalination technologies, expected to accoount for an increasing proportion of seawater desalination market in future, is essentially determined by the quality of RO membrane. However, the organic RO membranes, usually fabricated from cellulose acetate or polyimide, are susceptible to membrane fouling. This translates to a strict requirement for purity of feed-in seawater, and further,a high cost for seawater pretreatment. With excellent resistance to chemically harsh conditions and thermal and mechanical stability , the MFI-type zeolite membranes promise to be an ideal substitution for organic RO membranes due to better anti-fouling ability and ease of foulant cleaning. Study on fabrication and application of MFI-type zeolite membranes for aqueous solution desalination just started from past decade. To the best of our knowledge, MFI-type zeolite membranes used for RO seawater desalination is still not found. In this project, we will place emphasis on preparation of specific MFI-type zeolite membranes to be suitable for seawater desalination by RO and transport mechanism governed in subsequent RO seawater desalinaiton process. To be exact, four parts interrelated to one another are included in this project: preparation and structure regulation of the MFI-type zeolite membranes, identification and reparation of defects pores, the ion adsorption and exchange behavior between MFI zeolite and seawater and its influence on the ion rejection and water flux，finally, transport mechanism involved in RO seawater desalination with MFI-type membrane. Through a combination of experimental research and theoretical analysis, the preparation method of MFI-type membrane for RO seawater desalination and a transport model which used to describe ion and water transfer across membrane are to be established.

海水淡化是解决全球水资源危机的重要途径，反渗透作为海水淡化主流技术，其产水能力和能耗指标决定于反渗透膜的性能。常用的有机物反渗透膜易污染、对进水要求严格，海水前处理费用高。MFI型沸石分子筛膜稳定性好，是理想的有机物反渗透膜替代材料。本项目针对海水体系特点，开展用于海水淡化的MFI型分子筛膜制备及传递过程研究，具体内容包括：MFI型分子筛膜的制备与结构调控；分子筛膜缺陷识别与修复；MFI型分子筛与海水中主要离子的吸附与离子交换行为及其对离子截留和水分子跨膜传递过程的影响；MFI型分子筛膜海水淡化传递机理。通过本项目的实施，阐明分子筛膜反渗透过程中离子与水分子的传递机理，形成用于海水淡化的MFI型分子筛膜制备方法。

常用的有机物反渗透膜易污染、对进水要求 严格，海水前处理费用高。MFI 型沸石分子筛膜稳定性好，是理想的有机物反渗透膜替代材料。本项目针对海水体系特点，开展用于海水淡化的 MFI 型分子筛膜制备及传递过程研究， 具体内容包括：主要包括MFI分子筛膜水热合成工艺和机理研究、ZSM-5分子筛的制备及对阳离子的吸附研究、MFI分子筛膜缺陷修复及反渗透脱盐实验研究、铁掺杂的MFI分子筛膜的制备、铁骨架位掺杂分子筛膜对海水中不同阳离子分离性能的影响机理研究、面向海水脱盐的类分子筛膜（ZIF-8）稳定性及改性研究。本项目提出了一种新型微波二次生长制备MFI分子筛膜的方法。以多孔α-Al2O3为载体，通过微波二次生长法制备的MFI分子筛膜，在2.0MPa 0.1mol/L NaCl溶液中，膜通量为0.13 kg/m2h-1，Na+截留率超过75%。研究结果表明分子筛膜在海水反渗透脱盐领域有着潜在应用。